Process of preparing a siloxane copolymer

ABSTRACT

A process for preparing a cyclic siloxane copolymer, a water repellent composition and the use for treating porous substrates like concrete, especially reinforced concrete.

CROSS-REFERENCE TO RELATED APPLICATIONS AND STATEMENT REGARDINGFEDERALLY SPONSORED RESEARCH

None.

TECHNICAL FIELD

The present invention relates to a process for preparing a cyclicsiloxane copolymer, a water repellent composition for treating poroussubstrates like concrete, especially reinforced concrete.

BACKGROUND

Imparting or improving water repellency of a substrate is desired for anumber of substrates including organic or inorganic building components,for example, concrete, masonry, stucco, natural or artificial stone,ceramic, terracotta bricks, plaster board, fibre cement board, or othercement containing products, wood particle board, wood plasticcomposites, oriented strand board (OSB) or wood.

The desired water repellency properties are usually obtained by applyinga water-repellent composition to the external surface of a substrate soas to create a water repellent coating on the substrate which protectsthis substrate from weathering and other deterioration. At least theoutermost surface of building materials is treated in order to becomewaterproof.

Silicone compounds are used as water repellents due to their durability,good hydrophobicity and ease of application. First, silicone resins insolvent and methylsiliconates were used as silicone water repellentcompounds. Then followed siloxane and silane based products in solvents.Next generation of water repellents is generally water based forenvironmental reasons and ease of use. The active ingredients containsiloxanes, silicone resins and silanes (and combinations of them). Forexample, U.S. Pat. No. 5,074,912 discloses a water repellent compositionfor treating porous substrates with an emulsion containing a siloxanewhich is a linear methylhydrogen-methylalkyl siloxane copolymer or amethylhydrogen-methylalkyl cyclosiloxane copolymer. However this productpresents a Volatile Organic Content (VOC) of more than 100 g/l whereasemulsions having less than 100 g/l or even less than 50 g/l are desired.

WO200813423A1 describes silicone emulsions for imparting waterrepellency with a VOC content of below 100 g/l comprisingphenylsilsesquioxane. The emulsions according to this disclosure lackhowever reactivity and depth of penetration in order to fulfil therequirement for long term protection of structural concrete or otherporous building materials.

BRIEF SUMMARY OF THE INVENTION

The invention provides a process of preparing a siloxane copolymer byreacting

-   i) a 1-alkene containing from 8 to 12 carbon atoms-   ii) a cyclic siloxane having the formula:

wherein R is an alkyl radical having 1 to 3 carbon atoms; c is equal orhigher than 4.in the presence of a hydrosilylation catalyst so as to form a cycliccopolymer comprising the formula:

Where R′ is an alkyl group having from 8 to 12 carbon atoms and a+b=c,removing the unreacted alkene, isomerisation products of the alkeneformed and unreacted volatile cyclic hydrogensiloxane from the reactionmixture and the molar ratio alkene:cyclic siloxane being of at least1:1, preferably of 1.2:1 and more preferably 1.5:1.

DETAILED DESCRIPTION OF THE INVENTION

All amounts, ratios, and percentages are by weight unless otherwiseindicated. The articles ‘a’, ‘an’, and ‘the’ each refer to one or more,unless otherwise indicated by the context of specification. Thedisclosure of ranges includes the range itself and also anythingsubsumed therein, as well as endpoints. For example, disclosure of arange of 2.0 to 4.0 includes not only the range of 2.0 to 4.0, but also2.1, 2.3, 3.4, 3.5, and 4.0 individually, as well as any other numbersubsumed in the range. Furthermore, disclosure of a range of, forexample, 2.0 to 4.0 includes the subsets of, for example, 2.1 to 3.5,2.3 to 3.4, 2.6 to 3.7, and 3.8 to 4.0, as well as any other subsetsubsumed in the range. Similarly, the disclosure of Markush groupsincludes the entire group and also any individual members and subgroupssubsumed therein. For example, disclosure of the Markush group ahydrogen atom, an alkyl group, an aryl group, an aralkyl group, or analkaryl group includes the member alkyl individually; the subgroup alkyland aryl; and any other individual member and subgroup subsumed therein.

We have found that the process according to the invention provides atreatment which fulfils the following requirements

-   a) Durable against weathering.-   b) Show significant penetration into porous substrates. Some    surfaces of construction materials are exposed to significant wear    due to traffic. A surface treatment will therefore be removed by    abrasion. Some standards for water repellents therefore include an    abrasion test.-   c) Having a VOC level of below 100 g/l preferably below 50 g/l    according to ASTM D 5095-   d) Provide high water exclusion, therefore efficiently preventing    the ingress of chloride ions which can cause corrosion in the case    of iron reinforced concrete.

Alkylalkoxysilanes like n-octyltriethoxysilane fulfil most of theserequirements however they release alcohol during reaction with thesubstrate and are therefore high VOC products. E.g.n-octyltriethoxysilane which is frequently used for concrete protectione.g. as active in water based silicone water repellents has a VOCof >300 g/l.

In order to fulfil these requirements, the potential active of a low VOCwater repellent emulsion for reinforced concrete should be smallmolecular size to allow deep penetration into the pores of the concrete,chemically reactive to the substrate or crosslinkable with itself inorder to be durable, resistant to degradation at high pH and at the sametime, be non-volatile, However, to be non-volatile means that the activecompound needs to be above a certain molecular weight. Some of therequirements are thus conflicting.

The present invention relates to a process of reacting an alkene with acyclic siloxane to result in an effective low VOC water repellent activecompound. We have found that it is important to discard from thereaction products any unreacted reactants that are volatile, and that inaddition, a minimum ratio of alkene to cyclic siloxane is required.Furthermore, the chain length of the alkene should neither be too shortin order to yield a low VOC content nor too long in order to allow goodpenetration into porous substrates.

-   -   Preferably, the alkene is 1-octene, 1-dodecene or 1-isooctene.    -   Preferably, the molar ratio alkene:cyclic siloxane is at least        1.2:1.    -   Preferably, the molar ratio alkene:cyclic siloxane is at least        1.5:1.    -   Preferably, a mixture of cyclic siloxanes (structure I) is used        with c being comprised between 4 and 6.    -   Preferably, a is less than 3 and b is equal or greater than 2.    -   Preferably a platinum catalyst is used for the reaction.    -   Preferably, the composition according to the invention has a        Volatile Organic Content according to ASTM D 5095 below 100 g/l.    -   More preferably, the composition has a Volatile Organic Content        according to ASTM D 5095 below 50 g/l.

For example the reaction may be a case as illustrated below:

In order to provide the required low VOC, unreacted cyclic siloxane,unreacted olefin and isomerized olefin should be removed from thereaction product, for example by stripping, preferably using vacuum.

The siloxane copolymer produced by the process according to theinvention is usually not a pure compound, but a mixture of differentsiloxane copolymers, and this mixture is used to provide the compositionfor treating porous substrates.

The synthesis of the cyclic copolymer starting from cyclic methylsiloxanes leads to a mixture of actives that have different levels ofVOC. These cyclic siloxane can either be separated using know methodssuch as distillation or can be used as mixtures in the finalapplication. While a higher degree of substitution will lower the VOC itincreases as well the size of the molecule and decreases the reactivity.The optimum degree of substitution will therefore be a compromise thathas to be defined by VOC level required and performance testing.

The invention also provides a water repellent composition for treatingporous substrates comprising an emulsion which includes water, at leastone surfactant, and a siloxane copolymer obtained by the process definedherein.

In a preferred embodiment, the water repellent composition contains inaddition to the siloxane copolymer other components that can providehydrophobicity like organic oils, waxes or alkylsilanes under thepresumption that the VOC level is not increased above the requiredvalue.

In a preferred embodiment, the water repellent composition contains inaddition to the siloxane copolymer (cyclic copolymer) other componentswhich preferably do not significantly affect the VOC level like forexample, polysiloxanes or silicone resins.

The invention further provides a process for improving the waterrepellency of a substrate by treating it with a composition definedabove. In another preferred embodiment, improving the water repellencyof a substrate is done by including the composition into the startingmaterials or during manufacture of the substrate.

The invention provides the use of the siloxane copolymer obtainedaccording to the process to improve water repellency of a substrate byapplying the composition to the finished substrate or by including thecomposition into the starting materials or during manufacture of thesubstrate.

Useful substrates include organic or inorganic components.Alternatively, substrates include at least one of concrete, especiallyreinforced concrete, masonry, stucco, natural or artificial stone,ceramic, terracotta bricks, plaster board, fibre cement board, or othercement containing products, wood particle board, wood plasticcomposites, oriented strand board (OSB) or wood. Alternatively,substrates may include at least one of regular concrete, high strengthconcrete, stamped concrete, high performance concrete, selfconsolidating concrete, shotcrete, cellular concrete, lightweightaerated concrete, variable density concrete, foamed concrete,lightweight or ultra-lightweight concrete, rapid strength concrete,pre-stressed concrete or reinforced concrete for use in pavements,highways/roadways, bridges/overpasses, parking structures, stadiums,precast structures, tilt up structures, drainage pipes, tunnels orreservoir structures, concrete masonry units, concrete blocks, splitfaced blocks, natural stone or bricks for use on building facades orfoundations. Alternatively, substrates include at least one of stucco,natural or artificial stone, ceramic, terracotta bricks, plaster board,fibre cement board, or other cement containing products, wood particleboard, wood plastic composites, oriented strand board (OSB) or wood.

While the siloxanes copolymer according to (II) can be used as such orin a VOC exempt solvent water based products are preferred due to theirease of use and environmental advantages.

The invention extends to a water repellent composition for improving thewater repellency of substrates comprising an emulsion. Aqueous emulsionswherein the disperse oil phase is a cyclic copolymer of the formula (II)can be prepared by a number of different ways, for example, by

-   1) Combining    -   i) Water    -   ii) A siloxane copolymer obtained according to the process    -   iii) A surfactant-   2) Homogenizing the combined components to form an emulsion-   3) Optionally admixing additional water and additional ingredients.

Alternatively, the siloxane copolymer can be dispersed into an aqueoussolution or dispersion containing the surfactant under a constant mixingcondition. Still alternatively, part or all of the surfactant can becombined with the siloxane copolymer and the mixture in turn isdispersed into the water. The specific sequence of combination is notcritical and high shear homogenization is not absolutely necessary; theeffectiveness of the emulsification procedure depends on specificsurfactant package used and the procedure can be adjusted according tothe desired emulsion property. The cyclic copolymer of the formula (II)can be partially or completely hydrolyzed with water prior or duringemulsification to the corresponding silanols. This will not increase theVOC.

The emulsifier is a surfactant or mixture of surfactants having theability to stabilize an aqueous emulsion. The surfactant may be ananionic surfactant, cationic surfactant, non-ionic surfactant,amphoteric surfactant, or a mixture of surfactants. Non-ionicsurfactants and anionic surfactants are typically used in combination.Mixtures containing two or more non-ionic surfactants are preferred.

Representative examples of suitable non-ionic surfactants includecondensates of ethylene oxide with long chain fatty alcohols or fattyacids such as a C 12-16 alcohol, condensates of ethylene oxide with anamine or an amide, condensation products of ethylene and propyleneoxide, esters of glycerol, sucrose, sorbitol, fatty acid alkylol amides,sucrose esters, and fatty amine oxides. Silicone surfactant and fluorosurfactants can also be used. Representative examples of suitablecommercially available non-ionic surfactants include alcohol ethoxylatessold under the trade name BRIJ, Synperonic™, Renex™ by Croda, Edison,N.J., Lutensol® by BASF (Florham Park, N.J.). Some examples are BRIJL23, an ethoxylated alcohol known as polyoxyethylene (23) lauryl ether,and BRIJ L4, another ethoxylated alcohol known as polyoxyethylene (4)lauryl ether, Lutensol® XP-70 and Lutensol® XP-140, Synperonic 13-6 andSynperonic 13-12, all ethoxylated alcohols. Additional non-ionicsurfactants include ethoxylated alcohols sold under the trademarkTERGITOL® by The Dow Chemical Company, Midland, Mich., includingTERGITOL® 15-S-5, TERGITOL® 15-S-12, TERGITOL® 15-S-15, and TERGITOL®15-S-40. Sorbitan esters and their ethoxylated derivatives can also beused. Examples include those sold under the trade name Span™ and Tween™,such as Span 20, Tween 20, Span 80 and Tween 80, by Croda. Examples ofsilicone surfactant include silicone polyethers sold under the tradename Dow Corning® by Dow Corning Corporation, Midland, Mich., such asDow Corning® Q2-5247 Fluid and Dow Corning® Q2-5211 Superwetting Agent.Using a silicone superwetting agent can have an enhanced water repellenteffect. Such a superwetting agent can be incorporated as a part of theemulsifier package or added separately as an additive to the aqueousphase. When mixtures of surfactants are used, it is beneficial to haveat least one surfactant in the mixture have a low Hydrophile-LipophileBalance (HLB), for example, below 12, and the rest have a high HLB above12, such that the combined effective HLB is within the range 9-20,preferably 10-18. Particularly beneficial for the emulsion of theinventive cyclic copolymer is to use a combination of emulsifierscomprising at least one co-surfactant having a low HLB and insoluble inwater, and used in a fashion taught in U.S. Pat. No. 6,074,470.

Representative examples of suitable anionic surfactants include alkalimetal soaps of higher fatty acids, alkylaryl sulphonates such as sodiumdodecyl benzene sulphonate, long chain fatty alcohol sulphates, olefinsulphates and olefin sulphonates, sulphated monoglycerides, sulphatedesters, sulphonated ethoxylated alcohols, sulphosuccinates, alkanesulphonates, phosphate esters, alkyl isethionates, alkyl taurates, andalkyl sarcosinates.

Representative examples of suitable cationic surfactants includealkylamine salts, quaternary ammonium salts, sulphonium salts, andphosphonium salts. Representative examples of suitable amphotericsurfactants include imidazoline compounds, alkylamino acid salts, andbetaines.

The emulsifier can for example be used at 0.1 to 40%, preferably 0.5-10%by weight based on the weight of the cyclic copolymer. For optimumstability the aqueous phase should have a slightly acid pH, for examplepH 4 to pH 6.5. Buffer solutions can be used to stabilize the desiredpH. The concentration of cyclic copolymer in accordance with the presentinvention in such an oil-in-water emulsion can be from 1 to 85% byweight or alternatively from 5 to 80% by weight but is more preferablyfor example between 10 and 80% by weight of the total composition. If asecondary hydrophobing agent such as a polydimethylsiloxane is presentin the emulsion, the total concentration of cyclic copolymer plussecondary hydrophobing agent can for example be from about 1 up to 80%by weight of the total composition. The concentration of emulsifier insuch an oil-in water emulsion can for example be between 0.1 and 20% byweight of the total composition. Water can for example be present at 15to 89.5% by weight of the total composition. In each instance whenreferred to in % values the total present is 100% and the remainder ofthe emulsion is made up of other ingredients, typically water andsurfactant(s) and optional additives to a value of 100%.

Emulsions of cyclic copolymers in accordance with the present inventioncan contain various additives known in silicone emulsions, for examplefillers, colouring agents such as dyes or pigments, heat stabilizers,flame retardants, UV stabilizers, fungicides, biocides, thickeners,preservatives, antifoams, freeze thaw stabilizers, or inorganic salts tobuffer pH. Such materials can be added to the cyclic copolymer before orafter the cyclic copolymer has been emulsified.

In a preferred embodiment, the emulsion contains in addition to thesiloxane copolymer other components that can provide hydrophobicity likeorganic oils, waxes or alkylsilanes under the presumption that the VOClevel is not increased above the required value.

In a preferred embodiment, the emulsion contains in addition to thecyclic copolymer other components which preferably do not significantlyaffect the VOC level like for example, polysiloxanes or silicone resins.

The emulsion can be formulated to be in the form of a gel or a cream.This can be done by using thickeners such as bentonite ormontmorillonite in the emulsion or by having an active cyclic copolymercontent of above 60% to 85% in the emulsion. Such creams of highorganosilane content can be formed by preparing a mobile aqueousemulsion from a minor part of the organosiloxane with all of theemulsifier and water and mixing the remaining organosiloxane into theemulsion using a colloid mill, a high speed stator and rotor stirrer, ora pressure emulsification unit.

The invention encompasses the use of the composition to improve waterrepellency of a substrate by applying the composition to the finishedsubstrate. In a variant, the composition is used to improve waterrepellency of a substrate by including the composition in the startingmaterials before or during manufacture of the substrate.

The invention extends to a process for improving the water repellency ofa substrate by treating it with an emulsion having a Volatile OrganicContent according to ASTM 5095 below 50 g/l which includes water, atleast one surfactant, and a siloxane copolymer obtained by the processof

Reacting

-   (i) 1-octene-   (ii) a cyclic siloxane having the formula:

wherein R is methyl; and c is between 4 and 6,

-   in the presence of a platinum catalyst so as to form a cyclic    copolymer having the formula:

where R′ is octenyl, a is less than 3 and b is equal to or greater than2, a+b=c;

-   Removing the unreacted alkene and volatile cyclic siloxanes from the    reaction mixture and where the molar ratio alkene:cyclic siloxanes    is ≧1.5,-   wherein the substrate comprises at least one of regular concrete,    high strength concrete, stamped concrete, high performance concrete,    self consolidating concrete, shotcrete, cellular concrete,    lightweight aerated concrete, variable density concrete, foamed    concrete, lightweight or ultra-lightweight concrete, rapid strength    concrete, pre-stressed concrete or reinforced concrete for use in    pavements, highways/roadways, bridges/overpasses, parking    structures, stadiums, precast structures, tilt up structures,    drainage pipes, tunnels or reservoir structures, concrete masonry    units, concrete blocks, split faced blocks, natural stone or bricks    for use on building facades or foundations.

The invention also provides a use of an emulsion having a VolatileOrganic Content according to ASTM 5095 below 50 g/l which includeswater, at least one surfactant, and a siloxane copolymer obtained by theprocess of

Reacting

-   (i) 1-octene-   (ii) a cyclic siloxane having the formula:

wherein R is methyl; and c is between 4 and 6,

-   in the presence of a platinum catalyst so as to form a cyclic    copolymer having the formula:

where R′ is octenyl, a is less than 3 and b is equal to or greater than2, a+b=c;

-   Removing the unreacted alkene and volatile cyclic siloxanes from the    reaction mixture and where the molar ratio alkene:cyclic siloxanes    is ≧1.5;-   to improve water repellency of substrates by applying the emulsion    to the finished substrate wherein the substrate comprises at least    one of regular concrete, high strength concrete, stamped concrete,    high performance concrete, self consolidating concrete, shotcrete,    cellular concrete, lightweight aerated concrete, variable density    concrete, foamed concrete, lightweight or ultra-lightweight    concrete, rapid strength concrete, pre-stressed concrete or    reinforced concrete for use in pavements, highways/roadways,    bridges/overpasses, parking structures, stadiums, precast    structures, tilt up structures, drainage pipes, tunnels or reservoir    structures, concrete masonry units, concrete blocks, split faced    blocks, natural stone or bricks for use on building facades or    foundations

The invention also provides a process for improving the water repellencyof a substrate by treating it with a water repellent composition, havinga Volatile Organic Content according to ASTM 5095 below 50 g/l,comprising an emulsion which includes water, at least one surfactant,and a siloxane copolymer obtained by the process of

-   A) reacting-   (i) a 1-alkene containing from 8 to 12 carbon atoms-   (ii) a cyclic siloxane having the formula:

wherein R is an alkyl radical having 1 to 3 carbon atoms; c is equal toor higher than 4, in the presence of a platinum catalyst so as to form acyclic copolymer having the formula:

where R′ is an alkyl group having from 8 to 12 carbon atoms and a+b=c;

-   B) removing the unreacted alkene and volatile cyclic siloxanes from    the reaction mixture and where the molar ratio alkene:cyclic    siloxanes is ≧1;    wherein the substrate comprises at least one of regular concrete,    high strength concrete, stamped concrete, high performance concrete,    self consolidating concrete, shotcrete, cellular concrete,    lightweight aerated concrete, variable density concrete, foamed    concrete, lightweight or ultra-lightweight concrete, rapid strength    concrete, pre-stressed concrete or reinforced concrete for use in    pavements, highways/roadways, bridges/overpasses, parking    structures, stadiums, precast structures, tilt up structures,    drainage pipes, tunnels or reservoir structures, concrete masonry    units, concrete blocks, split faced blocks, natural stone or bricks    for use on building facades or foundations.

The invention also provides a use of the siloxane copolymer obtained bythe process of

-   A) reacting-   i) a 1-alkene containing from 8 to 12 carbon atoms-   ii) a cyclic siloxane having the formula:

wherein R is an alkyl radical having 1 to 3 carbon atoms; c is equal toor higher than 4, in the presence of a platinum catalyst so as to form acyclic copolymer having the formula:

where R′ is an alkyl group having from 8 to 12 carbon atoms and a+b=c;

-   B) removing the unreacted alkene and volatile cyclic siloxanes from    the reaction mixture and where the molar ratio alkene:cyclic    siloxanes is;    in a water repellent composition comprising an emulsion which    includes water, at least one surfactant and the siloxane copolymer    and having a Volatile Organic Content according to ASTM 5095 below    50 g/l, to improve water repellency of a finished substrate by    applying the composition to the substrate, wherein the substrate    comprises at least one of regular concrete, high strength concrete,    stamped concrete, high performance concrete, self consolidating    concrete, shotcrete, cellular concrete, lightweight aerated    concrete, variable density concrete, foamed concrete, lightweight or    ultra-lightweight concrete, rapid strength concrete, pre-stressed    concrete or reinforced concrete for use in pavements,    highways/roadways, bridges/overpasses, parking structures, stadiums,    precast structures, tilt up structures, drainage pipes, tunnels or    reservoir structures, concrete masonry units, concrete blocks, split    faced blocks, natural stone or bricks for use on building facades or    foundations.

EXAMPLES

These examples are intended to illustrate the invention and should notbe interpreted as limiting the scope of the invention set forth in theclaims.

Volatile Organic Content VOC

Determination of Volatile Organic (Compound) Content (VOC) forregulatory purposes is somewhat complex because expression of VOC is interms of mass/volume (i.e. grams/litre) as prescribed by theEnvironmental Protection Agency and numerous regional authorities in theUS and other countries; therefore VOC calculation can involvedetermination of individual component densities, accounting for exemptcomponents, and in water-based formulations, factoring out thewater—however, the VOC of an active ingredient or mix, or an emulsion ofthat active ingredient or mix is still chiefly dependent on the volatilecontent of the active components. For the invention, the volatilecontent is measured by the method ASTM 5095: “Standard Test Method forDetermination of the Nonvolatile Content (NVC) in Silanes, Siloxanes andSilane-Siloxane Blends Used in Masonry Water Repellent Treatments” thatincorporates an acid catalyst (p-toluene sulfonic acid) to aid in thereaction, and also adds a room temperature induction time to allow thereaction to occur before placing the test solutions in an oven. VOC isthen calculated per EPA method 24, according to the formula:VOC={100−NVC %−water %−exemptsol %)*density of product(g/ml}/{1−(density of coating (g/L)*water %)/(density ofwater*100)−(density of coating (g/ml)*exemptsol %)/(density ofexemptsolvent*100)}Depth of Penetration DOP

Depth of penetration is tested after the treatment has cured for atleast 7 days under standard conditions. For this the treated substrateis split with a chisel and a water-ink or water-soluble dye solution isapplied to the fresh surface. The parts of the substrate that aretreated will not be wetted by the ink solution while the untreated coregets stained. The distance of the so obtained line to the treatedsurface is measured with a ruler.

Water Exclusion

The water absorption of the treated concrete (or mortar) blocks overtime was measured by the RILEM (Reunion Internationale des Laboratoiresd′Essais et de Recherches sur les Materiaux et les Constructions) testII.∝(horizontal version), which is designed to measure the quantity ofwater absorbed by the surface (5 cm² exposed surface) of a masonrymaterial over a defined period of time. The water absorption in ml. ofeach block after various times is given. An untreated concrete block wasused as a reference (‘ref’).

Water Immersion Test

To determine the resistance of a treated substrate to water absorptionunder immersion conditions, a suitable concrete or mortar cube,measuring 2 inches per edge (Approx. 5 cm per edge) is treated toachieve a desired coverage rate—for instance, 0.5 litres/square meter or150 square feet/gallon. The treated substrate is cured for the requiredtime, weighed dry, and then immersed fully in water such that thesubstrate is completely covered. Water absorption is determined byremoving the substrates from the water at prescribed times, blottingwater from the surface, and weighing the blocks. For ease of comparisona set of untreated control blocks can also be included, and the waterabsorption can then be reported as a percent exclusion as compared tothe (average of) untreated controls. For instance, if an untreated cubeabsorbs 20% water by weight, and the treated cube absorbs 2% by weight,the water exclusion versus the untreated control would be 90%.

Synthesis of Cyclic Siloxanes

A 3-neck round bottom flask was equipped with an overhead mechanicalstirrer, thermometer, condenser, and pressure-compensated additionfunnel which was connected on top of the condenser.

A mixture of cyclic methylhydrogen siloxanes (containing approximately52% tetramethylcyclotetrasiloxane, 43% pentamethylcyclopentasiloxane and5% hexamethylcyclohexaasiloxane,) was poured into the reaction vesseland the addition funnel was charged with the alpha-olefin raw material.A small portion of the alpha-olefin was added to the reaction vessel andthe reaction mixture was heated to 70° C. The reaction was thencatalyzed with a standard Platinum hydrosilylation catalyst(chloroplatinic acid, 0.5 ppm Pt in the reaction) resulting in a rapidexothermic increase to ˜85-90° C.

Slow addition of the alpha-olefin was immediately started to maintainthe reaction temperature between 90-100° C. It was important to keep thereaction temperature at or above 90° C. so that a steady state could bemaintained where the reaction rate was equal to the addition rate,preventing an unsafe build-up of reactants, which could lead to a rapid,out of control exothermic reaction. After addition of the alpha-olefinwas complete, the reaction mixture was allowed to gradually cool to roomtemperature. Then, diallyl maleate was added (0.2 wt. %) as astabilizer.

Examples 1 to 4 Example 1

1-dodecene was reacted with a mixture of cyclic methylhydrogen siloxanesas described above using a molar ratio of alkene to SiH groups of 0.5:1.The reaction mixture was vacuum stripped. The product had a viscosity of28 mPas at 20° C., a density of 0.915 g/ml at 20° C. and a non-volatilecontent of 97% (volatile content of 3%) according to ASTM D5095. The VOCcontent of the fluid was therefore 27.5 g/l.

Example 2

1-octene was reacted with a mixture of cyclic methylhydrogen siloxanesas described above using a molar ratio of alkene to SiH groups of 0.5:1(it should be noted that the mixture of cyclic methylhydrogen siloxanesconsists out of molecules having 4, 5 or 6 SiH groups per mol dependingon the ring size). The reaction mixture was vacuum stripped. The producthad a viscosity of 16 mPas at 20° C., a density of 0.928 g/ml at 20° C.and a volatile content according to ASTM D5095 of 5%. The VOC content ofthe fluid was therefore 46.4 g/l.

Example 3

1-octene was reacted with a mixture of cyclic methylhydrogen siloxanesas described above using a molar ratio of alkene to SiH groups of 0.6:1.The reaction mixture was vacuum stripped. The product had a viscosity of20 mPas at 20° C., a density of 0.921 g/ml at 20° C. and a volatilecontent according to ASTM D5095 of 5%. The VOC content of the fluid wastherefore 46.1 g/l.

Example 4

1-octene was reacted with a mixture of cyclic methylhydrogen siloxanesas described above using a molar ratio of alkene to SiH groups of 0.7:1.The reaction mixture was vacuum stripped. The product had a viscosity of24 mPas at 20° C., a density of 0.919 g/ml at 20° C. and a volatilecontent according to ASTM D5095 of 3%. The VOC content of the fluid wastherefore 27.6 g/l.

The cyclic copolymers from examples 1-4 were tested for as waterrepellents by applying them to cured concrete slabs and measuring waterexclusion using the Rilem method. Concrete blocks were treated withapprox. 200 g/m² active and cured at RT for at least one week. The tablesummarizes the water uptake in ml for different times.

Rilem test 5 min 30 min 1 h 2 h 8 h 24 h Example 1 0 0 0 0.0 0.1 0.2Example 2 0 0 0 0 0.1 0.5 Example 3 0 0 0 0 0 0.05 Example 4 0 0 0 0 0.2— Ref not 0.6 2.3 3.9 4 >4 >4 treated

The test shows that the treatment strongly reduces the water absorptionversus an untreated reference. Mortar cubes were prepared according toEN 196-1 and treated by brushing them with the cyclic copolymers fromexample 1-4. The application rate was approx 180 g/m².

The cubes were dried for at least 1 week at Room Temperature and waterabsorption was measured by immersing them for during an extended periodinto water. The following table summarize the results, 3 cubes weretested per product and the average is reported.

Water uptake (%) 24 hours 48 hours 72 hours Example 1 0.50 0.65 0.85Example 2 0.57 0.75 0.98 Example 3 0.71 0.86 1.08 Example 4 0.60 0.740.96 Ref not treated 6.80 6.85 7.04

The test shows that the treatment strongly reduces the water absorptionfor a prolonged time versus an untreated reference. The DOP was measuredfor the same mortar cubes:

DOP mm Example 1 4.5 Example 2 4.5 Example 3 4.5 Example 4 4.0

The results show that the cyclic copolymers do penetrate deeply into theporous substrate as required to achieve good durability in constructionapplications.

Comparative Examples C1 to C5 Comparative Example 1

1-dodecene was reacted with a mixture of cyclic methylhydrogen siloxanesas described above using a molar ratio of alkene to SiH groups of 0.5:1.The reaction mixture was used as obtained without vacuum stripping. Theproduct had VOC content according to ASTM D5095 of 11%. The VOC contentof the fluid was therefore >100 g/l.

Comparative Example 2

1-octene was reacted with a mixture of cyclic methylhydrogen siloxanesas described above using a molar ratio of alkene to SiH groups of 0.6:1.The reaction mixture was used as obtained without vacuum stripping. Theproduct had VOC content according to ASTM D5095 of 12%. The VOC contentof the fluid was therefore >100 g/l.

Comparative Example 3

1-octene was reacted with a mixture of cyclic methylhydrogen siloxanesas described above using a molar ratio of alkene to SiH groups of0.25:1. The reaction mixture was used as obtained without vacuumstripping. The product had VOC content according to ASTM D5095 of 16%.The VOC content of the fluid was therefore >100 g/l.

Comparative Example 4

1-dodecene was reacted with a mixture of cyclic methylhydrogen siloxanesas described above using a molar ratio of alkene to SiH groups of0.25:1. The reaction mixture was used as obtained without vacuumstripping. The product had VOC content according to ASTM D5095 of 15%.The VOC content of the fluid was therefore >100 g/l.

Comparative Example 5 a and b

-   a) The VOC content of tetramethylcyclotetrasiloxane (purity >99%)    was measured according to ASTM D5095 and found to be 84%. The VOC    content of the fluid was therefore >100 g/l.-   b) The VOC content of pentamethylcyclopentasiloxane (purity ˜88%)    was measured according to ASTM D5095 and found to be 68%. The VOC    content of the fluid was therefore >100 g/l.

The comparative examples show that without removing unreacted alkene,isomerised alkene and unreacted volatile silicone hydrogen startingmaterials a VOC content of below 100 g/l is not obtained.

Example 5

Preparation of a low VOC emulsion. 160.16 g of the cyclic copolymersdescribed in example 2 were emulsified with 4.03 g of Brij L4, 5.9 g ofBrij L23 (72% active surfactant in water) and 230.45 g deionized waterusing the following procedure:

-   1) Water was added in to a stainless steel beaker set on a hotplate    (45° C.);-   2) Surfactants were added to the heated water while mixing with a    bench top mixer equipped with a propeller type mixing blade;-   3) The siloxane was added to the aqueous solution and mixed for 5    minutes;-   4) The content was then mixed with a rotor stator type mixer at    maximum speed for two minutes to form a coarse emulsion.-   5) The coarse emulsion was passed through a homogenizer 3 times at a    pressure of 10,000 psi.

A white emulsion having an active siloxane content of 40% was obtainedwith a particle size, determined with a Malvern Mastersizer in thevolume mode, of: d(0.1)=0.1887 microns, d(0.5)=0.364 microns,d(0.9)=0.541 microns.

The emulsion obtained had a VOC of <100 g/l. Concrete blocks weretreated with approx 200 g/m² active of the above emulsions. The contactangle of the treated unwashed blocks was determined to be 95.4 degrees.The contact angle was again measured after washing the blocks resultingin a contact angle of 124.2 degrees.

Example 6

A low VOC emulsion was made according to the following procedure. 200 gof the siloxane copolymer of Example 2, 3.05 g of Brij L23 (72% activein water) and 2.25 g of Brij L4 were mixed in a stainless steel beakerwith a magnetic stir bar. 294.71 g of water was added to the mixture andmixed with a bench top mixer equipped with a propeller and disperserblade. The content was further mixed using an Ultra Turrax® for 2minutes at maximum speed to form a coarse emulsion. The coarse emulsionwas passed three times through a homogenizer (SPX Corp., Charlotte,N.C.) at a pressure of 12,500 psi. A white emulsion was arrived havingan active siloxane content of 40% and a mono-modal particle sizedistribution with a median at 1.049 microns as measured by a MalvernMastersizer in the volume mode.

Concrete blocks were treated with approx 200 g/m² of the above emulsion.The contact angle of the treated unwashed blocks was determined to be117.3 degrees. The contact angle was again measured after washing theblocks resulting in a contact angle of 132.9 degrees.

Example 7

A low voc emulsion was made according to the following procedure. 160 gof the siloxane of Example 2, 6.24 g of Dow Corning® Q2-5247 Fluid and2.00 g of Dow Corning® 5211 Superwetting Agent were mixed in a bottleusing an Ultra Turrax® at maximum speed for one minutes. 234.08 g ofdeionized water was added to the mixture and mixed for an additional 4minutes to arrive at a coarse emulsion. The coarse emulsion was passedthrough the same homogenizer as in Example 6 three times at a pressureof 10,500 psi with cooling in between passes. A white emulsion wasarrived having an active siloxane content of 40% and monomodal particlesize distribution with a median at 0.469 microns as determined with aMalvern Mastersizer in the volume mode.

Concrete blocks were treated with approx 200 g/m² of the above emulsion.The contact angle of the treated unwashed blocks was determined to be44.7 degrees. The contact angle was again measured after washing theblocks resulting in a contact angle of 92 degrees.

To evaluate resistance to water absorption, the above emulsion wasapplied to three concrete cubes (2 inches on each edge) at a rateequivalent to approximately 150 square feet of surface per gallon oftreatment material, which is a common application rate for commercialpenetrating water repellents. The treated cubes were then cured for 7days RT before evaluating the resistance to water absorption byimmersion testing. After 1 day of immersion, the average waterexclusion, as compared to an untreated set of cubes, was 94.4%, andafter seven days of immersion the average water exclusion was greaterthan 80%.

The invention claimed is:
 1. Process for improving the water repellencyof a substrate by treating it with an emulsion having a Volatile OrganicContent according to ASTM 5095 below 50 g/I which includes water, atleast one surfactant, and a siloxane copolymer obtained by the processof Reacting (i) 1-octene (ii) a cyclic siloxane having the formula:

wherein R is methyl; and c is between 4 and 6, and where the molar ratioalkene:cyclic siloxane is ≧1.5, in the presence of a platinum catalystso as to form a cyclic copolymer having the formula:

where R′ is octyl, a is less than 3 and b is equal to or greater than 2,a+b=c; Removing the unreacted alkene and volatile cyclic siloxanes fromthe reaction mixture; wherein the substrate comprises at least one ofregular concrete, high strength concrete, stamped concrete, highperformance concrete, self consolidating concrete, shotcrete, cellularconcrete, lightweight aerated concrete, variable density concrete,foamed concrete, lightweight or ultra-lightweight concrete, rapidstrength concrete, pre-stressed concrete or reinforced concrete for usein pavements, highways/roadways, bridges/overpasses, parking structures,stadiums, precast structures, tilt up structures, drainage pipes,tunnels or reservoir structures, concrete masonry units, concreteblocks, split faced blocks, natural stone or bricks for use on buildingfacades or foundations.
 2. A process of utilizing an emulsion having aVolatile Organic Content according to ASTM 5095 below 50 g/I whichincludes water, at least one surfactant, and a siloxane copolymerobtained by the process of Reacting (i) 1-octene (ii) a cyclic siloxanehaving the formula:

wherein R is methyl; and c is between 4 and 6, and where the molarration alkene:cyclic siloxane is ≧1.5, in the presence of a platinumcatalyst so as to form a cyclic copolymer having the formula:

where R′ is octyl, a is less than 3 and b is equal to or greater than 2,a+b=c; Removing the unreacted alkene and volatile cyclic siloxanes fromthe reaction mixture; to improve water repellency of substrates byapplying the emulsion to the finished substrate wherein the substratecomprises at least one of regular concrete, high strength concrete,stamped concrete, high performance concrete, self consolidatingconcrete, shotcrete, cellular concrete, lightweight aerated concrete,variable density concrete, foamed concrete, lightweight orultra-lightweight concrete, rapid strength concrete, pre-stressedconcrete or reinforced concrete for use in pavements, highways/roadways,bridges/overpasses, parking structures, stadiums, precast structures,tilt up structures, drainage pipes, tunnels or reservoir structures,concrete masonry units, concrete blocks, split faced blocks, naturalstone or bricks for use on building facades or foundations.
 3. A processfor improving the water repellency of a substrate by treating it with awater repellent composition, having a Volatile Organic Content accordingto ASTM 5095 below 50 g/I, comprising an emulsion which includes water,at least one surfactant, and a siloxane copolymer obtained by theprocess of A) reacting i) a 1-alkene containing from 8 to 12 carbonatoms ii) a cyclic siloxane having the formula:

wherein R is an alkyl radical having 1 to 3 carbon atoms; c is equal toor higher than 4, and where the molar ration alkene:cyclic siloxanes is≧1, in the presence of a platinum catalyst so as to form a cycliccopolymer having the formula:

where R′ is an alkyl group having from 8 to 12 carbon atoms and a+b=c;B) removing the unreacted alkene and volatile cyclic siloxanes from thereaction mixture; wherein the substrate comprises at least one ofregular concrete, high strength concrete, stamped concrete, highperformance concrete, self consolidating concrete, shotcrete, cellularconcrete, lightweight aerated concrete, variable density concrete,foamed concrete, lightweight or ultra-lightweight concrete, rapidstrength concrete, pre-stressed concrete or reinforced concrete for usein pavements, highways/roadways, bridges/overpasses, parking structures,stadiums, precast structures, tilt up structures, drainage pipes,tunnels or reservoir structures, concrete masonry units, concreteblocks, split faced blocks, natural stone or bricks for use on buildingfacades or foundations.
 4. The process according to claim 3 in which thealkene is 1-octene, 1-dodecene or 1-isooctene.
 5. The process accordingto claim 3 in which the molar ratio alkene:cyclic siloxane is ≧1.5. 6.The process according to claim 3 in which a mixture of cyclic siloxanesis used with c being comprised between 4 and
 6. 7. The process accordingto claim 3 in which a is less than 3 and b is equal to or greater than2.
 8. A process of utilizing the siloxane copolymer obtained by theprocess of A) reacting i) a 1-alkene containing from 8 to 12 carbonatoms ii) a cyclic siloxane having the formula:

wherein R is an alkyl radical having 1 to 3 carbon atoms; c is equal toor higher than 4, and where the molar ratio alkene: cyclic siloxanes is≧1, in the presence of a platinum catalyst so as to form a cycliccopolymer having the formula:

where R′ is an alkyl group having from 8 to 12 carbon atoms and a+b=c;B) removing the unreacted alkene and volatile cyclic siloxanes from thereaction mixture; in a water repellent composition comprising anemulsion which includes water, at least one surfactant and the siloxanecopolymer and having a Volatile Organic Content according to ASTM 5095below 50 g/I, to improve water repellency of a finished substrate byapplying the composition to the substrate, wherein the substratecomprises at least one of regular concrete, high strength concrete,stamped concrete, high performance concrete, self consolidatingconcrete, shotcrete, cellular concrete, lightweight aerated concrete,variable density concrete, foamed concrete, lightweight orultra-lightweight concrete, rapid strength concrete, pre-stressedconcrete or reinforced concrete for use in pavements, highways/roadways,bridges/overpasses, parking structures, stadiums, precast structures,tilt up structures, drainage pipes, tunnels or reservoir structures,concrete masonry units, concrete blocks, split faced blocks, naturalstone or bricks for use on building facades or foundations.